1. Field of the Invention
This invention relates generally to devices and methods for securing a patch within a wellbore.
2. Description of the Related Art
Patches are used in uncased wellbores and wellbore sections to prevent collapse of the wellbore and/or preclude unintended fluid flow into or out of the wellbore. A patch is usually a tubular sleeve that is secured to the wall of the wellbore. The patch may be any desired length. The patch provides structural support and fluid sealing. There are two primary scenarios in which it is often desired to use a wellbore patch.
The first scenario occurs during drilling of a wellbore, particularly through unconsolidated earth. Because the wellbore is not yet lined with a casing, drilling mud and other fluids may undesirably flow into the surrounding earth formations from the wellbore. This not only results in the loss of fluids, but might contaminate production formations. In such an instance, a patch would provide the fluid sealing needed to prevent this fluid loss.
The second scenario occurs during production from an “open hole” wellbore, which lacks casing. In this situation, there is the danger that undesirable fluids, such as water, will migrate from the surrounding earth formation into the borehole. A patch could be placed along the wellbore in the area where fluid ingress occurs to block it.
In order to function correctly, a patch is secured against axial and rotary movement within the wellbore. Running of a drill string, for example, into the wellbore and through the patch will result in torsional and axial forces being imparted to the patch. The patch might be cemented into place. However, this operation is time consuming as the cement needs to be given time to set and later cure. Also, a cleaning tool is assembled and run into the wellbore to clean the excess cement from the patched area once the cement has been placed in the wellbore.
Currently there is not a relatively easy and acceptable method of securing a patch within a wellbore. The present invention addresses some of the above-noted problems of the prior art.